Robotics: Science and Systems VII

Slip, especially incipient slip, is a complicated process for soft_fingertips; and detection of this slip is important for stable manipulations by both human and robotic fingertips. Experimental_research has attempted to explain this phenomenon, but dynamic_changes during this process could not be fully delineated. We_propose here a dynamic model to investigate the sliding motion of_soft fingertips on a plane with friction. The fingertip is comprised_of a finite number of elastic, compressible and bendable cantilevers whose free ends act as infinitesimal contact points. The contact surface is afterward meshed using a finite element method based on the coordinates of the contact points. By introducing Coulomb's law_and contact compliance into each contact point, we were able to assess the frictional characteristics of the sliding motions of the fingertips. We also could successfully describe the dynamically localized displacements on the contact surface during stick-slip transition, displacements that represent the sliding motion of a_soft fingertip. This model can be applied to different shapes of_robotic fingertip, including the cylindrical and hemispherical_models tested here. We also performed experiments to validate the proposed simulation, including force/moment and vision setups.